JPH06289278A - Zoom lens unit - Google Patents

Abstract

PURPOSE:To provide a zoom lens unit having such features that a focal distance beyond a normal zooming range can be obtained, the unit is made compact and the operability is excellent, etc. CONSTITUTION:The unit is provided with a front lens group positioned opposite to an object and supported by a lens frame 8 which can be moved in an optical axis direction, movable lens groups supported by lens frames 9 and 10 which can be moved in the optical axis direction and an image forming lens group supported by a mount, and when the front lens group and the movable lens group are moved on the optical axis and moved to each prescribed position, the front lens group is separated from the optical axis while making a release shaft 13 to be an axis, so that the focal distance beyond the normal zooming range is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zoom lens unit, and more particularly to a technique of a zoom lens unit in which a front lens unit is separated from an optical axis to obtain a focal length outside a normal zooming range.

[0002]

2. Description of the Related Art Conventionally, in a zoom lens unit mounted on a home video camera or the like, zooming is mainly performed by changing the optical power of a variable magnification lens group supported behind a front lens group facing an object. It was done by axial movement.

Further, as means for obtaining a super wide state, which cannot be obtained by zooming by moving the variable power lens group, a method of mounting an attachment lens such as various wide converter lenses or JP-A-57-202511. There was a method such as the one described below in. That is, at least a part of the front lens group facing the subject is supported by a separate holder integrally connected to the lens barrel that supports the variable power lens group, and the holder is placed on the subject side.
It is intended to obtain a super wide state by rotating the holder by 180 ° and separating the holder from the optical axis.

[0004]

The conventional zoom lens unit has the following problems. In zooming, in the method of moving only the variable power lens group while fixing the front lens group, the moving amount of the variable power lens group becomes large, and the total length of the zoom lens unit becomes long. .

In addition, among the methods for obtaining the above-mentioned super wide state, in the method of mounting an attachment lens such as various wide converter lenses, since the attachment and detachment operation of the attachment lens is involved, the operability such as the quick-shooting property and the portability. However, the optical loss accompanying the attachment of the attachment lens cannot be ignored.

Further, according to the method disclosed in Japanese Patent Laid-Open No. 57-202511, when the holder is detached from the optical axis, the holder is placed closer to the subject than the zoom lens unit.
Since it is rotated 180 °, a large space is required in the direction in which the subject side of the zoom lens unit and the holder are detached, and it is not necessarily an effective method at present because miniaturization is desired for all products. There wasn't.

The present invention has been made to solve the above problems, and an object thereof is to provide a zoom lens unit which has a focal length outside the normal zooming range, has a short overall length, and is excellent in operability. There is.

[0008]

Such an object is achieved by the following means according to the present invention.

(1) It has a front lens group facing the subject, a movable lens group movable in the optical axis direction, and an imaging lens group, and at least one of the lens groups is moved in the optical axis direction. In the zoom lens unit that performs zooming, the front lens group and the moving lens group move on the optical axis, and when the both move to a predetermined position, the front lens group is separated from the optical axis. By doing so, a focal length outside the normal zooming range can be obtained, and (2) the front lens group facing the subject,
A zoom lens unit that includes a movable lens group that is movable in the optical axis direction and an imaging lens group, and performs zooming by moving at least one of the lens groups in the optical axis direction. When the lens group and the moving lens group move on the optical axis and both move to a predetermined position, the front lens group is separated from the optical axis, so that the focal length outside the normal zooming range is While being obtained, the movement of the front lens group and the moving lens group in the optical axis direction and the separation of the front lens group from the optical axis are performed by one motor.

[0010]

EXAMPLES The present invention will be described in more detail below with reference to Examples 1 and 2, but the present invention is not limited to these Examples.

First Embodiment A first embodiment will be described with reference to FIGS. 1 to 7. First,
1 is a sectional view of an optical axis of a zoom lens unit of the present invention, FIG. 2 is a rear view thereof, and FIG. 3 is a positional relationship diagram of a lens frame and a guide pin. As shown in FIGS. 1, 2 and 3, the fixed body 1
A cam cylinder 2 is radially fitted inside 2a and 2b, and a gear 2c is provided at the rear end of the cam cylinder 2. The cam cylinder 2 is attached to an external motor 3. The eccentric external gear 3a can rotate about the optical axis. Further, four guide pins 4a, 4b, 4c and 4d are fixed inside the cam barrel 2 by a guide pin fixing plate 5 and a guide pin fixing plate 6, respectively, in parallel with the optical axis. Further, the cam barrel 2 is regulated in the front-rear direction by a ring-shaped leaf spring 7 provided between the cam barrel 2 and the guide pin fixing plate 5.

In the lens frame 9 and the lens frame 10, a bush portion 9a having a hole formed in parallel with the optical axis, a bush portion 10a, and the bush portion 9a and the bush portion 10a, respectively, A U groove 9b and a U groove 10b are formed at positions symmetrical with respect to the optical axis, and the lens frame 9 and the lens frame 10 have the guide pins 4a and 4a.
It is slidably supported in the optical axis direction by b, 4c and 4d.

FIG. 4 is an exploded view of the cam barrel 2. As shown in FIG. 4, the cam barrel 2 is provided with cam grooves 2d and 2e for determining the movement paths of the lens frame 9 and the lens frame 10. When the cam barrel 2 rotates, the lens frame 9 and the lens frame 10 respectively move to the cam groove 2d and the cam groove 2d.
And, via the cam pin 11 and the cam pin 12 fitted in the cam groove 2e, they move independently in the optical axis direction.

The separation shaft 13 is supported on the fixed barrel 1 by separation shaft fixing tongues 1a and 1b in parallel with the optical axis. The lens frame 8 is provided with a bush portion 8a having a hole parallel to the optical axis.
It is supported so as to be slidable in the optical axis direction and rotatable in the direction perpendicular to the optical axis. As described above, the lens frame 9 moves in the optical axis direction with the rotation of the cam barrel 2 via the cam pin 11 fitted in the cam groove 2d. Since the lens frame 8 and the lens frame 9 move integrally in the wide-angle range in the optical axis direction, they must be in close contact with each other between the shift tele range and the wide range. Therefore, a spring 14 is provided between the flange portion 13a at the front end of the detaching shaft 13 and the lens frame 8 to urge the lens frame to the rear side, and further the lens frame 8
By inserting the connecting spring tip 15a of the U-shaped connecting spring 15 as shown in FIG. The lens frame 8 and the lens frame 9 are in close contact with each other.

A gear 8c is provided on the upper portion of the lens frame 8, and the lens frame 8 is rotated about the detachable shaft 13 by an external gear 16a attached to an external motor 16 according to the zooming state. By doing so, it is separated in the direction perpendicular to the optical axis.

FIG. 6 is a cross-sectional view of a connecting portion of the lens frame 8 and the lens frame 9. The lens frame 8 removed
However, when returning to the position before being detached, the axis of the lens group supported by the lens frame 8 and the optical axis are half with the optical axis provided in the lens frame 8 as the center, as shown in FIG. It is kept by fitting the circular stopper 8d and the flange portion 9c of the lens frame 9 centered on the optical axis.

A mounting seat 17 is connected to the rear side of the fixed barrel 1, and an imaging lens group is supported by the mounting seat 17, and the imaging surface is provided between the shift tele and the super wide. Moves along the optical axis. Further, an iris 18 that restricts the light rays of the zoom lens unit is fixed to the mounting seat 17.

Here, FIG. 4 showing the shapes of the cam groove 2d and the cam groove 2e formed in the cam barrel 2,
The lens frame 8, the lens frame 9, and the lens frame 10
The operation of the zoom lens unit of the present invention will be described with reference to FIG.

FIG. 7 is a movement diagram of the lens frame, showing a movement path L.
1, the moving path L2, and the moving path L3 are the moving paths of the lens frame 8, the lens frame 9, and the lens frame 10, respectively. It should be noted that L4 and L5 in FIG. 7 indicate the movement paths of the imaging lens group attached to the attachment seat.

First, between shift tele and tele, as the cam barrel 2 rotates, the lens frame 8 and the lens frame 9 are integrally combined as seen in the movement path L1 and the movement path L2. As it is, it retreats on the optical axis along the cam groove 2d through the cam pin 11. Also,
As seen in the movement path L3, the position of the lens frame 10 in the optical axis direction does not change.

In addition, between the tele and wide, the cam barrel 2
Of the moving path L1 and the moving path L
2, the positions of the lens frame 8 and the lens frame 9 in the optical axis direction do not change, and, as seen in the movement path L3, the lens frame 10 passes through the cam pin 12. And advances along the optical axis along the cam groove 2e.

Further, between wide and shift wide, the lens frame 8 and the lens frame 9 are integrally formed as seen in the moving path L1 and the moving path L2 as the cam barrel 2 rotates. With the cam pin 11 still connected, it advances on the optical axis along the cam groove 2d. In addition, as seen in the movement path L3, the lens frame
10 also advances on the optical axis along the cam groove 2e via the cam pin 12.

Further, between shift wide and super wide, the lens frame 9 does not move in the optical axis direction as seen in the moving path L2 as the cam barrel 2 rotates, but as described above, The lens frame 8 is
The gear 8c formed on the upper part of the above and the external gear 16a attached to the external motor 16 rotate around the separation shaft 13 so as to be separated in the direction perpendicular to the optical axis.

Here, other lens groups and lens frames are
If the lens frame 8 is detached without changing the position on the optical axis, the focal length of the zoom lens unit is suddenly shortened and the image becomes unnatural. Therefore, as seen in the movement path L3, as the lens frame 8 is separated from the optical axis, the lens frame 10 has a focal length of the zoom lens unit excluding the lens frame 8 that is shift wide. The cam pin 12 should be
Through the cam groove 2e, on the optical axis, and after the lens frame 8 is completely detached, the focal length of the zoom lens unit is superposed along the cam groove 2e via the cam pin 12 again. The lens moves forward on the optical axis as much as the focal length in the wide state.

When the lens frame 8 separated in the super wide state returns to a predetermined position in the shift wide state, the axis of the lens group supported by the lens frame 8 and the optical axis are as described above. As shown in FIG. 6, a semicircular stopper 8d centered on the optical axis formed on the lens frame 8 and a flange portion 9c centered on the optical axis of the lens frame 9 are held together. Be done.

In the zoom lens unit of the present invention, the image forming lens group is fixed to the mounting seat 17 as described above, and the image forming surface moves along the optical axis between the shift tele and the super wide. Along with that, an image pickup device (CCD) located on the rear side of the imaging lens group moves on the optical axis, C
It is a CD focus system.

Example 2 In Example 2, one motor is used to move the front lens group and the movable lens group in the optical axis direction and to separate the front lens group from the optical axis. It will be explained based on FIGS. 8 to 12. Note that the same or similar configurations as those of the first embodiment are designated by the same reference numerals and names as those of the first embodiment, and the description thereof will be omitted to avoid duplication.

FIG. 8 is a sectional view of the zoom lens unit of the present invention along the optical axis, and FIG. 9 is a rear view thereof. As shown in FIGS. 8 and 9, a cam barrel 2 is radially fitted inside the fixed barrel 1 at 2a and 2b, and a gear is formed at a rear end 2c of the cam barrel 2. The cam barrel 2 rotates around the optical axis by an external gear 3a attached to the external motor 3 and an external gear 3b to which the rotation of the external motor 3 is transmitted by the external gear 3a.

A gear 8c is formed on the upper part of the lens frame 8, and the lens frame 8 is centered on the detachable shaft 13 by an external gear 16a attached to a connecting cam 19 according to the zooming state. When it is rotated to, it is separated in the direction perpendicular to the optical axis.

Here, although the rotation of the external motor 3 is transmitted to the connecting cam 19 by the external gear 3a, the external gear 3c, and the external gear 3d, the rotation is always transmitted to the external gear 16a. Rather than continue, only when the lens frame 8 is detached in the direction perpendicular to the optical axis, rotation,
That is, the torque is transmitted. This will be described later. Others have the configuration described in FIGS. 1 to 3 of the first embodiment.

FIG. 10 is a development view of the cam barrel 2. As shown in FIG. 10, a lens frame 9 and a cam groove 2d and a cam groove 2f that determine the moving path of the lens frame 10 are formed. The difference from the first embodiment is the groove shape of the cam groove 2f.

The cam groove 2 formed in the cam barrel 2
d showing the shape of the cam groove 2f, and FIG. 12 showing the movement paths of the lens frame 8, the lens frame 9, and the lens frame 10, the zoom lens unit of the present invention The action of will be described.

In FIG. 12, a moving path L1, a moving path L2, and a moving path L3 are the moving paths of the lens frame 8, the lens frame 9, and the lens frame 10, respectively.

First, the operation described in the first embodiment is performed between shift tele-tele, tele-wide, and wide-shift wide.

Between shift wide and super wide, the lens frame 9 does not change its position in the optical axis direction as seen in the moving path L2 as the cam barrel 2 rotates, but as described above, The lens frame 8 is
By the gear 8c formed on the upper part of the above and the external gear 16a attached to the connecting cam 19, the gear 8c is rotated about the separation shaft 13 to be separated in the direction perpendicular to the optical axis.

Here, as described above, in the zoom lens unit according to the present invention, the connecting cam 19 includes the external gear 3a, the external gear 3c, and the external gear 3
The rotation of the external motor 3 is controlled by the d.
When transmitting to a, instead of constantly transmitting rotation,
The rotation is transmitted only when the lens frame 8 is separated in the direction perpendicular to the optical axis.

Here, FIG. 11 shows the state of the connecting cam 19 at a certain point between wide and shift wide. The connecting cam 19 includes an inner cam 19a, an outer cam 19b, and a cam pin 19
c and a cam spring 19d. The cam pin 19c is coupled to the inner cam 19a and fits in a cam groove 19e formed in the outer cam 19b. At the time of zooming, the external gear 3a, the external gear 3c,
The rotation of the external motor 3 is transmitted to the outer cam 19b by the external gear 3d, and the cam pin 19c is engaged with the cam groove 19e between shift tele and shift wide.
Since it slides on the inner cam 19a,
No torque is generated to rotate a around the axis.

However, between the shift wide and the super wide, the cam pin 19c reaches the cam groove unend portion 19f on the wide side of the cam groove 19e, so that the inner cam 19
The torque for rotating the inner cam 19a around the axis is generated in a, and the lens frame 8 includes the gear 8c formed on the upper part of the lens frame 8 and the external frame attached to the connecting cam 19. The gear 16a rotates about the separation shaft 13 to separate it in a direction perpendicular to the optical axis. Here, the cam groove 19e is bent immediately before reaching the cam groove non-end portion 19f, and further, the inner cam is formed by the cam spring 19d.
By urging 19a forward, the lens frame 8
The lens frame 8 is prevented from swinging when it is detached.

Here, in the torque transmission mechanism using the connecting cam 19, a plurality of external gears are used because of the difference in the rotation direction, the rotation angle of the motor, and the rotation angle of the member to which torque is finally transmitted. Must be used. Therefore,
As shown in FIG. 13, the external gear group is provided in one gearbox 3
By storing in e, compactness, noise such as gear rotation noise, lubrication condition, and appearance problem can be solved.

[0040]

Since the present invention is configured as described above, it has the following effects. That is, the effects of the invention according to claim 1 are as follows.

(1-1) In the zoom lens unit of the present invention, when zooming between shift tele and shift wide, in addition to the lens frame 10 corresponding to the zoom lens of the conventional zoom lens unit, the lens frame 8 , And the front lens group composed of the lens frame 9 moves on the optical axis. This makes it possible to reduce the overall length compared to conventional zoom lens units with similar performance.

(1-2) In the zoom lens unit of the present invention, when a super wide state is obtained, which cannot be obtained only by zooming by moving the front lens group and the variable power lens group in the optical axis direction, A part of the front lens group is separated in the direction perpendicular to the optical axis. As described above, since attachment / detachment lenses such as various wide converter lenses are not attached / detached, operability such as quick-shooting property and portability is not deteriorated, and optical loss caused by mounting the attachment lens is not caused.

(1-3) In the zoom lens unit of the present invention, since the lens frame 8 is detached in the direction perpendicular to the optical axis in the super wide state, a space is required in front of the front lens group. Not.

(1-4) In the zoom lens unit of the present invention, when the lens frame 8 is detached in the direction perpendicular to the optical axis, the lens frame 10 is a zoom lens unit excluding the lens frame 8. So that the focal length of the lens frame 8 is equal to the focal length in the shift wide state, the lens frame 8 is retracted through the cam pin 12 along the cam groove 2e along the optical axis.
After the completion of the disengagement, the zoom lens unit is advanced through the cam pin 12 again along the cam groove 2e so that the focal length of the zoom lens unit is equal to the focal length in the super wide state. The focal length of the zoom lens unit changes continuously, and the image becomes very natural.

The effects of the invention according to claim 2 are as follows.

(2-1) Effects of the invention of claim 1 (1-1), (1-2),
It has the same effect as (1-3).

(2-2) With the zoom lens unit of the present invention, zooming from shift tele to super wide is performed.
Since a single motor is used by using the torque transmission mechanism by the connecting cam 19, compactness and low cost are excellent, and noise such as gear rotation noise can be reduced.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an optical axis of a zoom lens unit according to a first exemplary embodiment.

FIG. 2 is a rear view of the zoom lens unit according to the first exemplary embodiment.

FIG. 3 is a positional relationship diagram of a lens frame and a guide pin of the first embodiment.

FIG. 4 is a cam barrel roll-opening diagram of the first embodiment.

FIG. 5 is a connection spring drawing of the first embodiment.

FIG. 6 is a combination diagram of the lens frames of the first embodiment.

FIG. 7 is a lens frame movement path diagram of the first embodiment.

FIG. 8 is a sectional view of an optical axis of a zoom lens unit according to a second exemplary embodiment.

9 is a rear view of the zoom lens of Embodiment 2. FIG.

FIG. 10 is a cam barrel roll-opening diagram of the second embodiment.

FIG. 11 is an explanatory diagram of a connecting cam according to the second embodiment.

FIG. 12 is a lens frame movement path diagram of the second embodiment.

FIG. 13 is an explanatory view of a connecting cam according to another embodiment.

[Explanation of symbols]

 1 Fixed body 1a, 1b Detachment shaft fixing tongue 2 Cam barrel 2c Gears 2d, 2e Cam groove 3 External motor 3a External gear 4a, 4b, 4c, 4d Guide pin 8 Lens frame 8a Bush part 8b Square hole 8c Gear 8d Stopper 9, 10 Lens frame 11, 12 Cam pin 13 Release shaft 13a Flange portion 14 Spring 15 Connection spring 15a Connection spring tip 16 External motor 16a External gear 17 Mounting seat 18 Iris 19 Connection cam 19a Inner cam 19b Outer cam 19c Cam pin 19d Cam spring 19e Cam groove 19f Cam groove end

Claims (2)

[Claims] 1. A front lens group facing a subject, a movable lens group movable in the optical axis direction, and an imaging lens group, wherein at least one of the lens groups is moved in the optical axis direction. In a zoom lens unit for zooming, the front lens group and the moving lens group move on the optical axis, and when both move to a predetermined position, the front lens group is separated from the optical axis. The zoom lens unit is characterized in that a focal length outside the normal zooming range can be obtained by doing so. 2. A front lens group facing a subject, a movable lens group movable in the optical axis direction, and an imaging lens group, wherein at least one of the lens groups is moved in the optical axis direction. In a zoom lens unit for zooming, the front lens group and the moving lens group move on the optical axis, and when both move to a predetermined position, the front lens group is separated from the optical axis. As a result, a focal length outside the normal zooming range can be obtained, and the movement of the front lens group and the moving lens group in the optical axis direction and the separation of the front lens group from the optical axis can be made one. A zoom lens unit characterized by being driven by a motor.